Dual purpose multi-brand monopole antenna

RELATED APPLICATIONS

0001The present application is based on, and claims priority from, Taiwan Application Serial Number 94107942, filed Mar. 15, 2005, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

00021. Field of Invention

0003The present invention relates to an antenna apparatus. More particularly, the present invention relates to a dual purpose antenna apparatus built in a wireless communication device for supporting the purposes of the multi-band mobile phone system and the global positioning system (GPS).

00042. Description of Related Art

0005The key development in communication technology has been the transfer from wired to wireless communication, such as by the popularization of wireless household phones and mobile phones. In the field of wireless communication, the signal is propagated in the air in the form of electromagnetic waves, where the bridge of the signals between the wireless device and the air is an antenna. That is to say, an antenna is certainly needed by a wireless communication device to transmit or receive electromagnetic waves, and is therefore an essential component of a wireless communication device.

0006In the conventional wireless communication device, the antenna apparatus is usually attached to the exterior of the device, such as a helix antenna attached on the exterior of a mobile phone. A variety of problems are inherent to this arrangement, however. For example, such an antenna is easily damaged by external force, the overhead of the circuit design is increased and the device is harder to carry. Furthermore, in accordance with the present design trend, many functions are integrated into a device, such as a mobile phone being able to receive and transmit signals in various frequency bands and/or having GPS functionality. Thus, the amount of components and antennas will substantially increase in the device, but the limited volume of the device must be maintained. For these reasons, the external antenna is increasingly unsuited for using in advanced wireless communication devices.

0007It is apparent that the compact antenna built in wireless communication devices will be a mainstream trend in the communications field. The conventional embedded compact antenna techniques comprise the flexible printed circuit (FPC), but they have some problems. Due to the FPC antenna being a kind of flat antenna, the length of the resonant path is limited within a footprint and is unable to flexibly extend, thus restricting the operating bandwidth of the FPC antenna.

0008This restriction becomes a great impact in a clamshell type mobile phone. In general, a clamshell type mobile phone comprises a lower cover having a keypad and an upper cover having a display. Because the antenna of the clamshell type mobile phone is often located on the top of the lower cover and near the upper cover, the center frequency of the antenna may shift due to the influence of the circuit located in the upper cover. If the center frequency of the antenna shifts out of the operating bandwidth of the system, the antenna is unable to receive and process the signals from base stations.

0009Moreover, the distance between the circuits located in the upper cover and the antenna is not constant, due to the folding motion of the clamshell type mobile phone. That is to say, the frequency shift value caused by the circuit located in the upper cover is also not constant. For this reason, the frequency shift is hard to be compensated for the shortness of the bandwidth in advance in an FPC antenna. The frequency shift will be more significant at low frequency than at high frequency and thus increases the degree of difficulty in designing the FPC antenna.

0010According to the foregoing description, an embedded compact antenna apparatus which is able to tolerate the frequency shift phenomenon is needed to ensure a good receiver sensitivity of the mobile phone apparatus, especially applying in the clamshell type mobile phone.

SUMMARY

0011It is therefore an objective of the present invention to provide an embedded compact antenna apparatus.

0012It is another objective of the present invention to provide a compact antenna apparatus with low cost, which has stable performance and is easily integrated into a clamshell type mobile phone system.

0013It is still another objective of the present invention to provide a dual purpose compact antenna apparatus, which is able to receive and transmit the signals of the multi-band mobile phone and GPS system.

0014It is still another objective of the present invention to provide a three-dimensional compact antenna apparatus such that various resonant paths can be formed on the antenna to increase the operating bandwidth.

0015In accordance with the foregoing and other objectives of the present invention, the invention provides a substrate made by an insulating material, such as plastic, and the substrate has at least two surfaces. One of the two surfaces is a cambered surface and the other one is a flat surface. There are two separate signal feeding points on the antenna: a first feeding point and a second feeding point. The two feeding points may be respectively located on the cambered surface or the flat surface. Accordingly, there are two antenna resonant paths extending from the first feeding point, one being a high-frequency path of a first radiating metal line and the other being a low-frequency path of the first radiating metal line. The high-frequency path irregularly extends on the flat surface and the low-frequency path irregularly extends on the cambered surface. The total length of the high-frequency path is shorter than the total length of the low-frequency path. Furthermore, there is a second radiating metal line extending from the second feeding point formed on the cambered and the flat surfaces, and there is a shorting path extending from the second radiating metal line formed on the flat surface, wherein an end of the shorting path is used to connect with the ground potential of the system.

BRIEF DESCRIPTION OF THE DRAWINGS

0016These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:

0017<figref idref="DRAWINGS">FIG. 1A</figref> is an oblique drawing of an antenna apparatus in accordance with an embodiment of the present invention;

0018<figref idref="DRAWINGS">FIG. 1B</figref> is another oblique drawing of an antenna apparatus in accordance with an embodiment of the present invention; and

0019<figref idref="DRAWINGS">FIG. 1C</figref> is a front view of an antenna apparatus in accordance with an embodiment of the present invention

DESCRIPTION OF THE PREFERRED EMBODIMENTS

0020Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

0021The basic objective of the present invention is to provide an embedded compact antenna apparatus with the dual purposes of being a multi-band mobile phone and having a GPS. Especially in a clamshell mobile phone, the antenna is able to provide a wider operating bandwidth. Therefore, the basic concept of the present invention is to form two antenna radiators made of metal materials on an insulating substrate, such that the signals respectively processed by the two radiators will not interfere with each other. One of the two radiators is used to be an antenna resonant path of the multi-band mobile phone system, and the other one is used to be an antenna resonant path of the GPS. The resonant path of the multi-band mobile phone system is further divided into a high-frequency path for the high-frequency signals and a low-frequency path for the low-frequency signals. Because the low-frequency signals need a longer path to achieve a resonant state with lower frequency and in order to reduce the grounding effect caused by the circuit board located in the upper cover of the clamshell mobile phone, the low-frequency path is formed on a cambered surface of the substrate to achieve a larger surface area, thus enabling optimization of the antenna radiator structure.

0022<figref idref="DRAWINGS">FIGS. 1A-1C</figref> all show an antenna apparatus <b>100</b> according to an embodiment of the present invention, wherein <figref idref="DRAWINGS">FIGS. 1A and 1B</figref> are the views of the antenna apparatus <b>100</b> from the left side and the right side separately, and <figref idref="DRAWINGS">FIG. 1C</figref> is a front view of the antenna apparatus <b>100</b>.

0023Referring to <figref idref="DRAWINGS">FIG. 1A</figref>, a substrate <b>102</b> of the antenna apparatus <b>100</b> can be made of any insulating material, such as plastic, and at least has one flat surface <b>104</b> and one cambered surface <b>106</b>. In the embodiment, a first feeding point <b>108</b> is located on the flat surface <b>104</b> and is used to connect with a mobile phone radio frequency (RF) module (not shown in the figure) so the RF signals can be received and transmitted by the antenna apparatus <b>100</b>, but the location of the first feeding point <b>108</b> is not limited by the embodiment in practice.

0024Due to the antenna apparatus <b>100</b> being able to be used in a multi-band mobile phone system and the operating frequencies of the present mobile communication systems approximately comprising 800 MHz, 900 MHz, 1800 MHz and 1900 MHz, the first feeding point <b>108</b> is connected by two antenna resonant paths (or one first radiating metal line) made of metal materials for the four frequency bands. One of the two resonant paths is a high-frequency path <b>200</b> used by 1800 MHz and 1900 MHz bands, and the other is a low-frequency path <b>300</b> used by 800 MHz and 900 MHz bands. According to antenna theory, lower frequency EM waves need a longer antenna resonant path to be radiated; therefore, the high-frequency path <b>200</b> can be formed on the flat surface <b>104</b>, and the low-frequency path <b>300</b> is formed on the cambered surface <b>106</b> because the low-frequency path <b>300</b> with a longer length needs a larger surface area to be formed to achieve a wider operating bandwidth. In the embodiment, the high-frequency path <b>200</b> is designed to process signals with a frequency range of 1710 MHz to 1990 MHz, and the low-frequency path <b>300</b> is designed to process signals with a frequency range of 824 MHz to 960 MHz. In these frequency ranges, almost all of the frequency bands used by the conventional mobile communication systems can be covered.

0025Referring to <figref idref="DRAWINGS">FIG. 1B</figref>, there is a second feeding point <b>110</b> located on the flat surface <b>104</b> acting as an entrance for the GPS signals to the antenna apparatus <b>100</b>. In the embodiment, the second feeding point <b>110</b> is used to connect with a GPS RF module (not shown in the figure) for GPS signals to be received by the antenna apparatus <b>100</b> and is located on the flat surface <b>104</b>, but the location of the second feeding point is not limited by the embodiment in practice.

0026The main purpose of the second feeding point <b>110</b> is to connect with a second radiating metal line <b>400</b>. The operating frequency of the present GPS is about 1575 MHz; therefore, the length of the second radiating metal line <b>400</b> will be a little longer than the length of the high-frequency path <b>200</b> shown in <figref idref="DRAWINGS">FIG. 1A</figref>. Thus, the second radiating metal line <b>400</b> can be formed on the cambered surface <b>106</b> for avoiding an over-routing density on the flat surface <b>104</b>. In addition, a shorting path <b>500</b> may be formed to connect to the second radiating metal line <b>400</b>, and it includes a shorting point <b>506</b> to avoid degrading the stability of the GPS signals by the high-frequency path <b>200</b> or low-frequency path <b>300</b> when they are operated at the same time. The stability of the GPS signals can be enhanced in the operation when the shorting point <b>506</b> is connected with the ground potential of the system. Similarly, the shorting point <b>506</b> is located on the flat surface <b>104</b> in the embodiment, but the location of the shorting point <b>506</b> is not limited by the embodiment in practice.

0027The forms of each resonant path of the antenna apparatus <b>100</b>, that is, the high-frequency path <b>200</b>, low-frequency path <b>300</b>, the second radiating metal line <b>400</b> and the shorting path <b>500</b> are not limited in the embodiment. But according to the results of the related experiments, the forms of each resonant path in the following description are able to provide a better performance (i.e. a better gain and bandwidth).

0028Referring to <figref idref="DRAWINGS">FIG. 1A</figref> again, it can be seen that the high-frequency path <b>200</b> is formed by connecting four line segments in order that extend from the first feeding point <b>108</b>: a line segment <b>202</b>, a line segment <b>204</b>, a line segment <b>206</b> and a line segment <b>208</b>. The angle between the line segment <b>202</b> and the line segment <b>204</b> is about 90° to 120°, and the adjacent angles among the line segments <b>204</b>, <b>206</b>, and <b>208</b> are both about 45° to 60°.

0029Referring to <figref idref="DRAWINGS">FIGS. 1A and 1C</figref>, it can be seen that the low-frequency path <b>300</b> is formed by connecting eleven line segments in order that extend from the first feeding point <b>108</b>: a line segment <b>302</b>, a line segment <b>304</b>, a line segment <b>306</b>, a line segment <b>308</b>, a line segment <b>310</b>, a line segment <b>312</b>, a line segment <b>314</b>, a line segment <b>316</b>, a line segment <b>318</b>, a line segment <b>320</b> and a line segment <b>322</b>. The angles between the line segment <b>302</b> and the line segment <b>304</b>, between the line segment <b>304</b> and the line segment <b>306</b>, between the line segment <b>306</b> and the line segment <b>308</b>, between the line segment <b>308</b> and the line segment <b>310</b>, between the line segment <b>310</b> and the line segment <b>312</b>, between the line segment <b>312</b> and the line segment <b>314</b>, between the line segment <b>314</b> and the line segment <b>316</b>, between the line segment <b>316</b> and the line segment <b>318</b>, between the line segment <b>318</b> and the line segment <b>320</b> and between the line segment <b>320</b> and the line segment <b>322</b> are all about 30° to 120°.

0030Referring to <figref idref="DRAWINGS">FIGS. 1B and 1C</figref>, it can be seen that the second radiating metal line <b>400</b> is formed by connecting four line segments in order that extend from the second feeding point <b>110</b>: a line segment <b>402</b>, a line segment <b>404</b>, a line segment <b>406</b> and a line segment <b>408</b>. The angle between the line segment <b>402</b> and the line segment <b>404</b> is about 60°, and the adjacent angles among the line segment <b>404</b>, <b>406</b>, and <b>408</b> are both about 90°.

0031Referring to <figref idref="DRAWINGS">FIG. 1B</figref>, there is a shorting path <b>500</b> extending from the joint of the line segment <b>402</b> and the line segment <b>404</b> to a shorting point <b>506</b>.

0032The material of the antenna apparatus <b>100</b> according to the embodiment is also discussed herein. The material of the substrate <b>102</b> is polycarbonate (PC), due to PC being easily shaped and thus beneficial to mass production. However, metal materials can't be easily attached to PC; therefore, all the paths on the substrate <b>102</b> surface, the high-frequency path <b>200</b>, low-frequency path <b>300</b>, the second radiating metal line <b>400</b> and the shorting path <b>500</b> should be formed by acrylonitrile butadiene styrene (ABS), due to metal materials being easily attached to ABS. Finally, all the paths on the substrate <b>102</b> are coated with any metal material for completing the antenna apparatus according to the embodiment.

0033It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.